Angela Helen Martin has followed the PhD Programme at the Faculty of Engineering and Science, with Specialization in Natural Sciences, Scientific Field Coastal Ecology.
- Trial lecture starts at 10:30
- Public defence starts at 12:30
Title of trial lecture: “The role of benthic and pelagic marine ecosystems for climate change mitigation”
Read the thesis in the Norwegian Research Information Repository
Disputation chair: Elna Svege, Department of Natural Sciences
Assessment committee
- First Opponent: Senior Researcher Martin Biuw, PhD, Institute of Marine Research, Norway
- Second Opponent: Professor, Dr. Clare Bradshaw, Stockholm University, Sweden
- Chair of Assessment Committee: Senior Adviser Marte Sodeland, PhD, University of Agder
Supervisors in the doctoral work:
- Main Supervisor: Professor Esben Moland Olsen, University of Agder
- Co-supervisor: Associate Professor Grace K. Saba, Rutgers University, USA
Summary of thesis
The ocean carbon cycle is increasingly recognized for its importance in absorbing greenhouse gases emitted by human activities and thereby delaying or reducing the severity of the impacts of climate change on land. The role of fish and other marine vertebrates in the oceans biological carbon pump are not well defined yet have urgent relevance as the combination of overfishing and the climate crisis alter distribution, behaviour and threaten populations. My aims in this thesis were to 1) improve understanding of how marine vertebrates influence carbon in marine ecosystems; and 2) consider the ecological carbon functions of fish in the context of sustainable management of fisheries and blue carbon approaches. I found that marine vertebrates influence carbon and other nutrient flows in ecosystems where they occur, from surface waters to the seabed, with tangential effects on connected habitats, from the open ocean to terrestrial environments. However, quantification of the scale of their influence is limited by relatively few empirical studies. I then turned my attention to empirical research on wild coastal fish and found that carbon production for three species ranged from 5.3-50.5mg C day-1; faecal pellets from four species had rapid sinking rates (mean 2,550 - 6,390 M day-1); and carbon was a substantial component of faecal material collected from 10 species (17-38% of dry weight). Given the wealth of ecological data available and affordable visual sampling technologies, I highlight machine learning techniques that could be used to expedite knowledge of marine vertebrate carbon functions and the associated outcomes. Moving on to the second aim of the thesis, I found that a fishery exploiting a recovered population of European hake (Merluccius merluccius) landed less than a third of the carbon stored in hake biomass, compared to 96% when fishing the depleted population; the stock of organic carbon in the recovered population was 6.5 times larger than that stored in the depleted population; however, the subsequent increase in hake landings removed more organic carbon in fish biomass from the system than when fishing the depleted population. I conclude that ecosystem approaches to fisheries management that incorporate climate-based objectives would need to consider what constitutes sustainable fishing based on factors including disturbance to organic carbon in fish populations, overall ecosystem carbon function and sediment disturbance alongside greenhouse gas emissions from fuel. Finally, in Paper V, I advise that the ecological roles of marine fish necessitate consideration for truly sustainable fisheries management and are likewise essential to maximise the success of blue carbon approaches. I recommend greater scientific attention to ecological roles of marine animals and policy approaches that similarly value fish for their environmental, cultural, societal, and economic benefits. In summary, marine vertebrates are integral to marine carbon cycling and sequestration and consideration of fish functional roles is essential for sustainable management of marine ecosystems and resources.
What to do as an online audience member
The disputation is open to the public. To follow the trial lecture and the public defence online, register on Zoom.
We ask online audience members to join no earlier than 10 minutes in advance. After these times, you can leave and rejoin the meeting at any time.
Opponent ex auditorio:
Deadline for the public to pose questions is during the break between the two opponents. Questions ex auditorio can be submitted to disputation chair Elna Svege.
Contact person
- victoria.belous@uia.no
- Phone
- +47 38 14 23 46